Recent advances in animal models of experimental myopia and ocular development may offer important frameworks for the development of new and effective treatment strategies in humans. work with chicks and tree shrews has clearly established the importance of postnatal visual experience in the regulation of eye growth, contributed to our understanding of ocular mechanisms controlling refraction, and has made inroads toward understanding the biochemical mechanisms of ocular growth control. How does this work relate to humans? Research with non-human primates is the critically important link between animal experiments and human treatments. In this project, we will be examining the regulation of ocular refraction in the common marmoset. We have chosen this primate because of this small size and relatively rapid development compared to other primates. Earlier work by PI with the marmoset suggests that the growth rate of the eye is set during an early sensitive period, and visual deprivation produces axial myopia after an initial delay, even if the eye is not yet myopic when the deprivation ends. These results may have some relationship to developmental myopia in children which, once started, persists or worsens. In the proposed experiments we will examine the mechanism of early refractive change at the sensory, histological and biochemical levels. The main work on this project is being conducted at the New England College of Optometry (Boston, MA), but could no be accomplished without the assistance of the New England Regional Primate Research Center. The primate center is the principal resource for veterinarian and husbandry advice, and several experiments involving the rearing of young marmosets